Furnace for burning pulverized fuel and other substances.



No. 817,989. PATENTBB APR. 17, 1906.

` A. M. BBSN D. A. BETTINGTUN.

PURNAUB FOR BURNING PULVERIZBD FUEL AND OTHER SUBSTANGES. Prummel rum)Px xa. moa.

4 suma-,snm n.

No. 817,939. PATENTE!) APR. 17, 1906. A. M. ROBESON C. BBTTINGTON.FURNACE FORBURNING PULVERIZBD FUEL AND OTHER SUBSTANCES.

APPLICATION FILED APB 13. 1905.

NTHCNY M. ROBESON, OF

BETTINGT i our M. Rossburg, Transvaal,

son, resi T Q and CLA, A`orrori, residing at Bos ton, ing4 uffolk,"State of Massaehuset, ted certain new and useful '1 i -s in Furnaces forBurnin P or other Substances, of whic i is a full, clear,l and exact deni such as will enable others skilled in o which it appertains to makeand s e of the objects of the invention is to so A. struct a furnacethat the roducts of comustion and unconsumed fiiel will double ack uponthemselves before escaping from the retort of the furnace.

Another object is to construct a furnace so that the retort will extendin an upward rlirection and be provided with means for projecting thematerial to be burned into the retort in an upward direction.

Another object is to so construct a furnace that the slag and unconsumedproducts will fall directly out of the retort of the furnace and into apit or other means for receiving the same.

Another object is to construct a furnace so that the slag and otherunconsumed` roducts will fall from the retort into a pit and be conveyedtherefrom.

Other objects will appear from the hereinafter description.

It is a well-known fact that when coal or other material pulverized orreduced to a fine powder is introduced into a furnace with the properamount of air combustion is practical] perfect, rovided the fuel suplied, the qua ity of the Ifuel, and the air-supp y remain constantwithin narrow limits; but when any of these features change either thefire goes out or it burns very inefliciently. We have experimented withmany forms of furnaces on a working scale for burning owdered fuel andother material and find tliat while one form may answer well for onekind of material it will be found unsuitable for another. Furnaces whichhave been heretofore constructed for burnin coal with three or four percent. of ash, W ich makes no elinkers, clog up and are inoperative in ashort time if I on of Letters Patent.

- 4hprll18,1905. Serial No. 255,470.

OFFICE.

URG,TRANSVAAL, AND CLAUDE A.

, MASSACHUSETTS.

vvl)i FUEL AND OTHR SUBSTANCES.

Patented .April i7, 1906.

fed with coal containing as high as twenty per cent. of ash. Furnaceswhich have heretofore been constructed having a given crosssection willpossess a certain critical capacity which if exceeded in even theslightest degrec results in the oint of combustion gradually creepinurin tlie direction of the flow of the gases and finally going out. Thisis a common fault of a furnace using powdered coal or other material inwhich the course of the gas is not directly back on itself duringcombustion and is due to the fact that the mixture of the powdered fueland other material and air is really of an explosive nature, havin adefinite but slow rate of transmission o the point of explosion orcombustion. The point of combustion commences to cree forward the momentthe speed with whic the mixture of air and fuel introduced into thefurnace exceeds that of the rate of transmission of the point ofexplosion, the result being that the flame soon blows out. The rate oftransmission of the point of explosion depends on the inainmability ofthe dust and the temperature of the mixture. No practical control can behad over the inaminability if any kind of coal is to be burned,

and therefore it remains that the tempereture of the mixture and itsvelocity only can be varied in order to make the point of explo sionstable,

By causin the mixture to turn upon itself ,and return a ongside of theincoming stream or separate and return along two sides of it or spreadout in a circular or mushroom form and return on all sides, as would bethe case if the retort were vertical and circular and the incomingstream central, not only is a regenerative action secured, which initself would insure the point of explosion being close to the point ofentrance to the furnace of the explosive mixture, but the very act ofchang ing the direction of the flow of the gases changes the velocity ofportions of the stream and at the turning-point by producing eddies,Vlespecially if the form of the furnace is unsymmetrical as regardsideal flow-lines, and thereby brings about the condition of decreasingvelocity coincident with increasing temperature, thus creating a verystable condition.

After many experiments we have discovered that the vertical form offurnace is very efficient for carrying out our invention and is IOO theone we prefer if fuel or other materiad i which produces slag whilebeing burned i A material return or double back upon them' selves forthe purpi se of controlling the point of combustirn can be ap lied to ahorizontal or inclined. furnace, per iaps to greater advantage forcertain services than to a vertical furnace. Therefore we do not confineourselves to any particular form of furnace.

As before stated, for certain kinds of fuel or other material-namel r,those containing over four per cent. of a siag-forming ash-a form offurnace, if powdered material is to be burned, which will rid itself ofthe accumulations of slag, is imperative. We have experimented with manydevices and forms of furnaces to attain this object and find the furnacewhich we will hereinafter describe to be very eflicient fer thispurpose. The slag whlch it is desired to remove from the furnace isliquid at the normal working tem` perature of the combustion-chamber orretort, but becomes viscous whenever it reaches a place where, for anyreason, there is a lower tem erature. Also, the slag which causes troube is that which impinges on the walls of the retort and runs down themand not that which remains in suspension in and is carried along withthe products of combustion. These sus ended particles soon cool offenough after leaving the retort to render them incapable of sticking tosurfaces, and therefore finally settle down with the dustash and give nofurther trouble.

The yertical form cf furnace lends itself best to the disposal of slagfor two reasons: (a.) The area of a horizontal secticn of the verticalretort being always much smaller than that of a horizontal furnace ofthe same output, the radiation of heat into the slagpit, which must bedirectly under the peripheral walls cf the retort, will be much less inthe vertical form, thereby allowing the deposited slag to become colderand render the operation of removing it less trying to workmen. (b) Thearticles of slag which are carried along W1th the products of combustionare moving in a downward direction toward the slagit just before leavingthe combustion-cham er, and being relatively heavy and of a globularform instead of making a turn of ninety degrees into a horizontaldirection along with the gases and dust they continue thelr rectilineardirection and roject themselves into the slag-pit. It is t eseconsiderations that make the vertical form of furnace preferable to thehorizontal for coals containing large quantities of slag; but all of theprinciples on which we base our invention can be applied to horizontalor inclined furnaces.

The preferred type of our invention is illustrated 1n the accompanyingdrawings, which s part of this application, in which the ferencecharacters refer to similar e different views.

a horizontal section of the fur- `he line 1 of Fig. 2. Fig. 2 is a onthe line 2 2 of Fig. 1. tss-section on the line 3 y verticalcross-section Fig. 5 is a cross-sec- 6 is cross-section of the line 6 6of Fig.

B is the cornbustioq C is a slag-pit immetl tort.

D represents a pi e for -f the retort pulverize coal or i if to beburned and mixed with ai of this ipe D is turned upward an upwardly intothe retort. This i. pipe which rojects into the retort` covered witlli)some refractory mate' may be water-jacketed.

The retort has its walls E formed o fractcry material, owing to theintense produced within it, and it should be mad as to permit freeexpansion, especially in a. verwhich are preferably kept at a shortdistance from the walls of the retort in order to form an air-space G tolessen heat radiation.

In the furnace here shown the horizontal section of the retort isrectangular; but it may be made in any other form which thecircumstances of the case demand. The to of the retort is arched withfire-brick; but 1t may be formed of fiat refractory material and couldbe closed by means of a waterjacketed metallic cover, if desired.

At the bottom of the retort on one side is an opening H for the escapeof the products of combustion. This o ening is in the form of a singlearch in one of) the long sides of the retort; but it may be formed ofmore than of the short ends of the retort, the essential thing bein thatthe outlets shall be as lowI down in tlie retort as possible, so thatthe, time of combustion ma be as long as possiucts of combustion becaused to double back u on themselves. The height of the retort bustionof all the combustible particles of the material fed into the retortbefore they are permitted to esca e.

On the side of t e retort opposite the o ening H are thecleaning-openinvs J an an o ening K, which is made use of for igniting te fuel and as an inspectiondoor, The covers L of these doors are made,preferably,

of slabs of refractory material suspended by tical direction. Itis alsosurrounded on three 9 sides by the walls F of the boiler-setting,

ble for a given height o retort and the prod- IIO one arch, or it couldbe formed in one or both s ould be such as to insure a sufficientcomproducing an air-blast wi th a pulverizingmachine, thereby blowingthe powdered material directly into the retort as fast as produced, orit may be of a form which delivers the pulverized material without anair-blast, in which case the pulverized material is blown into thefurnace through the medium of any air blast producing apparatus intowhich is fed the ulverized material by means of an suitab e feeder,suitable means being provi ed to vary the proportions of the air andpulverized material delivered to the furnace. In su plying the airinstead of forcing it througli the pipe D with pulverized material theair may be mixed with the material as it is projected from the upper endD of the pipe, suitable means being provided for introducing the airseparate from the fue] at this point.

The method of operating the furnace is as follows: In starting thefurnace a brazier filled with wood and greasy waste is introducedthrough the hole H and lighted. The brazier is formed so as to allow ofa moderatelyfree passage of the powdered fuel through it when placedover the end D of the fuelsupply pipe. The blast is then started at avery low rate, and the material is fed into the retort at such a rate asnot to smother the fire in the brazier. The powdered materialimmediately partially ignites and gradually heats up the retort. In a shtime the retort is sufficiently hot to allow of the removal of thebrazier, after which the rate of combustion will be increased untilworking conditions are reached. While we have here stated that thebrazier is passed throu h the opening H to start the fire, yet it isunderstood that 1t may be started in any other manner, as the startinmaterial may be passed into the retort trough the openin at the bottomthereof. After the retort as been thorou hly heated the material to beburned may le varied at will without there being the slightest tendencyon the part of the fire to go out, or the air and material sup ly can becompletely cut off for a considera e time, provided the doors and draftsbe closed, and the furnace then be started up in a short time by simplyrenewing the material and air-supply. It is preferable to so regulatethe drafts of the furnace as to make the pressure within the retortabout the same as that of the atmosphere to avoid loss of heat throughinfiltration of air; but if for any reason it is desired to have thepressure within the furnace greater or less than that of the atmos herethe furnace will work equally well. Afltber the fire is started in theretortthe products of combustion and the burning material are projectedupwardly in the retort until they reach a certain point, which variesaccordin to the force With Which the material is injected into theretort,

and other conditions, whereupon the products of combustion and theignited material will fall downward or double back upon themselves. Theproducts of combustion will )ass out through the opening H into theboiler-chamber and circulate around the boiler-tubes and ass out throughthe opening P. The solid particles of unconsumed material, such as slagand other substances, will fall throu h the bottom of the retort andinto the s ag-pit. If any of the liquid slag falls up against the innerwalls of the retort, it will trickle downthe sides thereof and, owing tothe construction of the bottom of the retort, as shown at S, and thesides, as shown at S', will also drop down into the slagpit. If theslag-pit is provided with a waterreceptacle, such as shown, the slagwill fall into the water in the said receptacle. The endless conveyer Wbeing operated will remove the slag from the receptacle or the pit andthrow it onto the carrier X. Any of the ash or solid materials carriedfrom the retort into the boiler-chamber will fall on the oor of theboiler-chamber and can be thrown out throu h the openings M*l in thebottom of said c amber and into the carrier, the carrier operating toremove or convey both the slag from the slag-pit and the ash from theboilerchamber in the construction shown.

Of course it is to be understood that if the endless carrier is not usedfor removing the slag the said slag may be removed through the extendedportion U of the slag-pit in a manner Well known.

As many changes could be made in the above construction and manyapparently` widely-different embodiments of our invention could be madewithout departing from the scope thereof, we intend that all mattercontained in the above description or shown in the accompanying drawingsshall be interpreted as illustrative and not in a limitin sense. Wedesire it also to be understood that the language used in the followingclaims is intended to cover all of the generic and specific features ofthe invention herein described and all statements of the scope of theinvention, which as a matter of language mi ht be said to falltherebetween.

aving now describedlour invention, what we claim as new, and desire tosecure by Letters Patent, is*

1, In a furnace, a combustion-chamber closed, exce t at or nearthebottom thereof and means or injectin a finely-divided solid fuel and asu 4porter o combustion substantially vertically into the chamber, theopen part of the chamber permitting `the escape of products ofcombustion.

' 2, In a furnace, a combustion-chamber closed except at or near thebottom and means for injecting amixtme of fuel and a supporter ofcombustion substantially verti- IIO cally intdthe chamber, the open partof the chamber permitting the esca e of products of combustion andunconsume material.

3. In a furnace, a combustion-chamber, means for injectingfinely-divided solid fuel .substantially vertically into the chamber inone direction, said chamber having an exit adjacent to the point wherethe fuel is injected, whereby the products of combustion and unconsumedfuel are caused to double back in the combustion-chamber before passingfrom the chamber.

4. In a furnace, a combustion-chamber, a pipe through which pulverulentfuel is injected substantially vertically in one direction into thechamber, said chamber having an exit therein adjacent to the end of thepipe whereby the products of combustion are caused to double back in thecombustionchamber before passing therefrom.

5. In a furnace, a combustion-chamber closed except at or near thebottom thereof, a pjipe or nozzle at the bottom of the chamber a jacentto the opening from thev chamber, through which finely-divided solidfuel is projected substantially vertically into the chamber, the openingom the chamber permitting the escape of products of combustion.

6. In a furnace, a vertical rcombustionchamber closed except at or nearthe bottom, means for supplying to the combustionchamber fuel and asupporter of combustion, said means being so arranged with respect tothe combustion-chamber as to cause at least some of the burning fuel tobe supported or held in suspense by the incoming material.

7. In a furnace, a combustion-chamber, and a single means for supplyingto the combustionfehamber a mixture of fuel and a supporter ofcombustion, said means being so arranged with respect to thecombustionchamber as to cause the fuel burning in the chamber to besupported and held in suspense by the incoming material.

8. In a furnace, a combustion-chamber having an opening near its lowerend for the passage of products of combustion and anv other openingadjacent thereto for the passage of unconsurned products, and means forinjecting material to be burned into the comd bustion-chamber soarranged as to keep the material in suspense While burning.

9. In a furnace, a combustion-chamber having an opening near the lowerend thereof for the passage of products of combustion and anotheropening for the passage of unconsumed material and means for injectingmaterial to be burned upwardly into the combustion-chamber.

10. In a furnace, a combustion-chamber open at or near the bottomthereof for the passage of products of combustion and unconsumedmaterial, a pit under the combustion-chamber the inner surface of theWalls of the combustion chamber overhanging the walls of the pit andmeans for injecting the material upwardly into the combustiolb chamber.

il. In a furnace, a combustion-chamber, open at the bottom thereof topermit the passage of unconsumed material, the said combustion-chamberhaving an opening near the bottom thereof for the passage of products ofcombustion, a pit under the combustionchamber, the inner surface of theWalls of the combustion-chamber overhanging the inner surface of thewalls of the pit, and means for injectin pulverulent material upwardlyinto the com ustion-chamber.

12. In a furnace, a combustion-chamber havin an opening for the passageof products o combustion, a pipe near said cpenin and through which apulverulent materia may be injected into the combustionechambersubstantially vertically in one direction, and the products ofcombustion are caused to double back upon themselves in the oppositedirection before passing through the openin from the combustion-chamber.

13. n a furnace, a combustion-chamber, a pipe through which apulverulent fuel may be projected upwardly into the combustionchainber,the combustion-chamber being open only at or near the bottom thereofnear t ie end of said pipe whereby the products of combustion andunconsumed material Will be caused to double back and move downwardlybefore passing from the combustion chamber.

14. In a furnace, a combustion-chamber loo open only at or near thebottom thereof for the assage of products of combustion, said comustion-chamber surrounded by an airspace and having a channel in itswall communicating with said space through which aA 105 gas may besupplied to the combustionchamber, means for controlling the su ply ofgas, and means for injecting upwardly into thel combustion-chamberpulverulent materia 15. In a furnace, a combustion-chamber having anopening near the bottom thereof for the passage of products ofcombustion, said combustion-chamber also being open at its lower endthrough which slag or other uni 15 consumed material may fall, a devicefor catching said material, means for conveyin away said material and anupWardlyFeXten ing pipe through which material to be burned Emy beinjected into the combustion-cham- 12o 16. In a furnace, acombustion-chamber, having an c ening for the passage of products of comustion and another opening in the bottom thereof for the escape of slagor 125 other unccnsumed material, a second chamber adjacent to thecombustion-chamber into which the products of combustion pass having ano ening in the bottom thereof through whic ash or other material carried13o IIO by the products of combustion may escape, and means extendinfrom the opemng in the bottom. of the com ustion-chalnbcr to the openingin the second chamber adapted to remove both the slag and ash.

17. In a furnace, a combustion-chamber and a boiler-chamber, separatedby a wall having an opening through which roducts of combustion )ass tothe boiler-c amber, the bottom of t e combustion-chamber provided withan opening for the escape of slag and the bottom of the boiler-chamberprovided with an o ening for the escape of ash or other materia and anendless carrier extending from the opening under the combustion chamberto the opening under the boiler-chamber for the purpose of removing boththe sla and ash.

18. In a 'urnace, a vertical combustionchamber closed except at or nearthe bottom, means for supplying to the combustionchamber pulverulentfuel and a supporter of combustion, said means being so arran ed withrespect to the combustion cham er that the incoming fuel will support orhold in suspense some of the particles of the burning fuel.

19. In a furnace, a vertical combustionchamber closed except at or nearthe bottom and a sin le means for supplying to the combustion-c amber amixture of fuel and a supporter of combustion, said means bein so arraned with respect to the combustlonchamer as to cause some of the articlesof the burning fuel to be supporte or held in suspense by the incomingmixture.

20. In a furnace, a combustiomchamber open at or near its lower end forthe passage of products of combustion and unconsum'ed material and meansfor injecting material to be burned into the combustion-chamber, thesaid means being so arranged as to keep some of said material insuspense while the material is burning.

21. In a furnace, a combustion-chamber, means for su plying to thecombustionchamber a fuel) and a supporter of combustion, said meansbeing so arranged as to cause the burning fuel and products ofcombustion to double back and to envelop the incomin fuel.

22. n a furnace, a combustion-chamber, closed except at or near thebottom thereof, means for supplying pulverulent fuel into the chambernear where it is o en, the parts being so arranged as to cause tEeproducts of combustion and unconsumed particles to double back andenvelop the incomin fuel before passing from the combustion-c amber.

In witness whereof I have hereunto set my hand7 at Johannesburg, SouthAfrica, this 11th day of March, 1905.

ANTHNY M. ROBESON.

In presence of- THos. GREY, W. J. CLARKsoN.

In witness whereof I have hereunto set my hand, at the city of New York,in the county of New York and State of New York, this 31st day ofJanuary, 1905.

CLAUDE A. BETTINGTON.

In presence of- LoUIs N. WHEALTON, T. R. RIcHARDs.

